Metabolomics and biochemical analyses in functional active components of ripe mulberry fruits

Mulberry fruits possess wide application across multiple sectors, including food processing, medicine, cosmetics, and the brewing industry, while also being recognized as natural antioxidants. However, fundamental knowledge regarding the metabolites underpinning antioxidant capacity variation among mulberry cultivars remains limited. In this study, we examined total flavonoid and phenolic contents alongside metabolite profiles in four mulberry cultivars exhibiting great distinct color phenotypes, and further clarified the relationships between these metabolites and total antioxidant capacity. Results revealed that AS with dark-colored mulberries fruits displayed significantly elevated flavonoid and phenolic contents, along with heightened total antioxidant capacity, compared to their light-colored counterparts. Using LC-MS-based untargeted metabolomics, a total of 629 differentially accumulated metabolites were identified across six comparative groups, and were predominantly associated with the biosynthesis pathways of flavonoids and phenolic compounds. WGCNA analysis further demonstrated that the contents and composition of metabolites significantly affects the antioxidant capacity of ripe mulberry fruit among varieties. 10 hub flavonoids and phenols of two key modules were identified, and could be considered as potential biomarkers of antioxidant capacity. This study greatly expands our knowledge of the bioactive constituents of ripe mulberry fruits, and highlights the potential application of mulberry plants as antioxidants functional ingredients and nutraceuticals.